Question

Cate grame de NaCl trebuie să camtarim pentru a prepara 500ml soluție 0,2M?

Answer 1

C.M.= concentratia molara
n=nr de moli
V=volum
m=masa
M=masa molara
C.M.=nNaCl/Vsol, adica 0.2=nNaCl/500, adica nNaCl=0.2*500=100 moli
nNaCl=mNaCl/MNaCl
MNaCl=23+35.5=58.5 mg/mmol
Deci 100=mNaCl/58.5, rezulta mNaCl=58.5*100=5850 mg NaCl, adica 5.85 g NaCl